[1] JBS Int Inc, Res & Dev Grp, Res & Dev, Bethesda, MD 20852 USA
[2] NIDA, Div Epidemiol Serv & Prevent Res, NIH, Bethesda, MD 20892 USA
[3] Univ Pittsburgh, Ctr Educ & Drug Abuse Res, Pittsburgh, PA USA
[4] NIDA, Div Epidemiol & Prevent Res DESPR, NIH, Bethesda, MD 20892 USA
[5] NIDA, Epidemiol Res Branch, Bethesda, MD 20892 USA
[6] NIDA, Vulnerabil Res Program, Bethesda, MD 20892 USA